Aaron has got a good article on sun exposure: http://www.bassmaster.com/blog/sun-enemy-protect-yourself
Growing up in NW Ohio I worked the fields in the summer for cash. I never wore a shirt. Now, I work outside in electrical substatations. This past year I have had 3 surgeries to remove “spots” on my head, shoulders, neck, and back. I don’t think raccoon eyes are cool anymore. I wear SPF clothing and sunblock. You know, I might look like I work in a flour factory, but I don’t feel zapped like I used to.